Foundation Types

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  • Grade beam - while not seen in typical slab-on-grade diagrams - it is the thickened part of a slab-on-grade - [1]
  • Slab is easier and cheaper to build than a pier and beam foundation. [2]
  • Grade Beam - [3]
  • Grade beam is the thickened outer edge of the slab foundation. [4]
  • Spread footing - 'inverted T' actually holds the pressure on the soil. Grade beam functions like a beam - spanning 2 deep piles, not relying on soil underneath for support. [5]
  • Grade beams connect column foundations together - [6]
  • Slab foundations are used on flat lots [7]. Supported directly be ground.
  • Shallow and deep are 2 general classes. Deep ones go down to bedrock. [8]


  • Grade beam is min 8" wide, and depth is the length of span it supports [9]
  • Compared to typical foundation, uses less concrete.